Specificity of glycosphingolipid recognition by Entamoeba histolytica trophozoites.
The ability of purified glycosphingolipids to enhance liposome-stimulated Entamoeba histolytica actin polymerization was assessed as a means of defining the specificity of mammalian cell membrane lipid glycan recognition by this parasite. Synthetic liposomes containing a variety of individual glycosphingolipids bearing neutral, straight-chain oligomeric glycans with galactose or N-acetylgalactosamine termini stimulated rapid (90-s) polymerization of amoeba actin. Glycans with terminal N-acetylglucosamine residues were not stimulatory at all or were only weakly stimulatory. Glycans with glucose, N-acetylglucosamine, galactose, and N-acetylgalactosamine as the penultimate residue were recognized. Attachment of N-acetylneuraminate to the terminal residue of a stimulatory glycosphingolipid eliminated activity; attachment of fucose to the penultimate sugar reduced activity. Glycans with a terminal beta 1-4 or 1-3 glycosidic bond were most effective; glycans with terminal alpha 1-4 or 1-3 glycosides were less effective. The activity of glycans with both beta- and alpha-linked terminal glycosides was inhibited by lactose, suggesting recognition of both configurations by a single amoeba protein. The ability of liposomes to stimulate actin polymerization reflected the extent of liposome phagocytosis.
Bailey
G B
GB
Department of Biochemistry, Morehouse School of Medicine, Atlanta, Georgia 30310.
Nudelman
E D
ED
Day
D B
DB
Harper
C F
CF
Gilmour
J R
JR
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002474:Cell-Free System; D004748:Entamoeba histolytica / Q000378:metabolism*; D004910:Erythrocyte Membrane / Q000378:metabolism*; D005690:Galactose / Q000494:pharmacology; D006028:Glycosphingolipids / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007785:Lactose / Q000494:pharmacology; D008081:Liposomes; D010587:Phagocytosis / Q000187:drug effects; D011108:Polymers; D013329:Structure-Activity Relationship
D000199:Actins; D006028:Glycosphingolipids; D008081:Liposomes; D011108:Polymers; D007785:Lactose; D005690:Galactose